Solid-state warning light with environmental control

ABSTRACT

The present invention relates generally to warning lights, and more specifically, to solid-state (LED) warning lights whose operation is modulated in response to environmental conditions, generally under the supervision of a microprmcessor or dedicated control circuit. LEDs are used in warning lights, but not in an effective way. Typically, the LED driving circuits are electrically inefficient and in some cases, there is an attempt to minimize the power that is supplied to the LEDs. The invention employs environmental sensors which allow the operation of the LEDs to be optimized: for example: LED intensity can be increased in response to poor ambient visibility, duty cycle can be decreased in response to a lack of power, and the LEDs can be de-rated in response to high temperature conditions. Many other advantages of the invention are described, including the use of light control film, buck boost and buck down driver circuits, external communication circuits and microprocessor control.

The present invention relates generally to warning lights, and morespecifically, to solid-state (LED) warning lights whose operation ismodulated in response to environmental conditions, generally under thesupervision of a microprocessor or dedicated control circuit.

BACKGROUND OF THE INVENTION

Warning lights are useful and desirable on many types of vehicles,machinery, and other objects (buildings, towers, people, animals, etc.)to announce the presence, location, operation mode, status, or functionof the vehicle, machine, process or event. The nature of warning lightsrequires them to be employed in harsh physical environments, often inremote or difficult-access locations, and with limited availability ofelectrical power.

Solid-state light emitting diodes (LEDs) are well-suited for use inwarning lights due to characteristics such as good electricalefficiency, small size and weight, and rugged construction compared toother light sources such as incandescent bulbs. However, existing LEDwarning lights suffer from a number of problems, including thefollowing: circuit complexity (resulting in high production cost andpoor reliability), low electrical-to-luminous power conversionefficiency (resulting in unwanted higher operating temperatures andunwanted higher electrical power consumption), and limited ability tooperate from a range of electrical supply voltages.

In particular.

-   -   LED constant voltage circuits require the use of series        resistors, causing unwanted loss of electrical power as heat;    -   LED constant current circuits require the use of additional        circuitry to measure and control electrical power exciting the        LED; and    -   unregulated circuits require heat producing series resistors and        are limited to operation over a narrow range of electrical        supply voltages, therefore limiting their application.

One strategy for controlling LEDs and LED assemblies is to minimize theoutput power of the LEDs with respect to ambient lighting levels. Inother words, some LED driver systems try to provide only enough power toensure that the LEDs are visible against the backdrop of the ambientlighting. While such an approach might minimize power consumption, itdoes nothing to improve on the actual efficiency of the conversion frompower to light. More important, by reducing the contrast between thewarning light and the ambient lighting, the possibility of warningsbeing missed, increases. In many applications this is a tradeoff that issimply not acceptable.

There is therefore a need for an improved LED warning light

SUMMARY OF THE INVENTION

It is therefore an object of the invention to provide a novel warninglight which offers some operational advantage over the prior art.

One aspect of the invention is defined as a warning light comprising anassembly of light emitting diodes (LEDs); a control circuit operable todrive the LEDs; one or more environmental sensors coupled to the controlcircuit; the control circuit further including: means for receiving dataand/or measurements from the environmental sensors; means forcalculating optimal operating parameters for the LEDs, based on theenvironmental data and/or measurements; and means for driving the LEDsin accordance with said calculated optimal operating parameters.

Another aspect of the invention is defined as a warning lightcomprising: a plurality of separate LED sub-assemblies on rigid printedcircuits, attached to a base circuit board that provides both mechanicaland electrical connection between the rigid circuit boards and the basecircuit board, the separate LED sub-assemblies being pointed indifferent directions; a control circuit operable to drive said separateLED sub-assemblies; one or more environmental sensors coupled to saidcontrol circuit; the control circuit further including: means forreceiving data and/or measurements from the environmental sensors; meansfor calculating optimal operating parameters for the separate LEDsub-assemblies, based on the environmental data and/or measurements; andmeans for driving the separate LED sub-assemblies in accordance with thecalculated optimal operating parameters; allowing the assembly of amulti-directional warning light module without the need for costlyflexible or bendable circuit board materials.

A further aspect of the invention is defined as a warning lightcomprising: an assembly of light emitting diodes (LEDs); a controlcircuit operable to drive the LEDs; one or more environmental sensorscoupled to the control circuit; the control circuit further including:circuitry for receiving data and/or measurements from the environmentalsensors; circuitry for calculating optimal operating parameters for theLEDs, based on the environmental data and/or measurements; and circuitryfor driving the LEDs in accordance with the calculated optimal operatingparameters.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of the invention will become more apparent fromthe following description in which reference is made to the appendeddrawings in which:

FIG. 1 presents a schematic diagram of circuit in a broad embodiment ofthe invention;

FIG. 2 presents a schematic diagram of an integrated LED) module (ILM)including an LED Buck Boost Channel (LBBC) in an embodiment of theinvention;

FIG. 3 presents a schematic diagram of an integrated LED module (ILM)including an LED Buck Down Channel (LBDC) in an embodiment of theinvention;

FIG. 4 presents a schematic diagram of a warning light circuit in aCM-LM (Control Module—LED Module) configuration including an LBBCcircuit in an embodiment of the invention;

FIG. 5 presents a schematic diagram of a warning light circuit in aCM-LM configuration, including an LBDC circuit in an embodiment of theinvention;

FIG. 6 presents an exemplary physical layout of a planar ILM includingan LBBC circuit in an embodiment of the invention;

FIG. 7 presents an exemplary physical layout of a planar ILM includingan LBDC circuit in an embodiment of the invention;

FIGS. 8 and 9 present top and front views, respectively, of acylindrical warning light using an ILM including an LBBC circuit, in anembodiment of the invention;

FIGS. 10 and 11 present top and front views, respectively, of a planarwarning light including light-control film, in an embodiment of theinvention;

FIGS. 12 and 13 present top and front views, respectively, of a warninglight having a square cross-section, and including light-control-film,in an embodiment of the invention;

FIGS. 14 and 15 present top and front views, respectively, of a warninglight having a rectangular cross-section, employing multiple ILMs, andincluding light-control-film, in an embodiment of the invention;

FIGS. 16, 17 and 18 present front top and isometric views, respectively,of a cylindrical warning light employing multiple side-emitting LEDs, inan embodiment of the invention;

FIGS. 19, 20 and 21 present front, top and back views, respectively, ofa warning light employing multiple LEDs with optical lenses, in anembodiment of the invention; and

FIGS. 22 and 23 present front and rear isometric views, respectively, ofa warning light employing multiple LEDs with optical lenses, in anembodiment of the invention.

DESCRIPTION OF THE INVENTION

An electrical schematic diagram of a warning light which addresses oneor more of the objects outlined above, is presented in FIG. 1. Thiswarning light includes an assembly of light emitting diodes (LEDs) 10, acontrol circuit 12 operable to drive the LEDs 10 and one or moreenvironmental sensors 14 which are electrically connected to the controlcircuit 12. Specific examples will be described in greater detailhereinafter, but may include, for example, devices to sense thefollowing environmental conditions:

-   -   ambient temperature;    -   internal temperature;    -   ambient light level;    -   emitted light level;    -   relative humidity;    -   liquid moisture;    -   mechanical tilt;    -   vibration;    -   physical shock;    -   marine wave height and period;    -   air pressure;    -   barometric pressure;    -   solar cell voltage;    -   battery voltage;    -   supply voltage.        Typically, these sensors will be mounted on a circuit board        within the warning light, but may also be mounted externally or        on an outside surface of the warning light.

A number of environmental sensors and their application strategies aredescribed hereinafter, but two that are particularly useful are themonitoring of supply voltage and ambient temperature. The controlcircuit 12 can adjust to the available power level of the supplyvoltage, varying the frequency and/or duty cycle of pulses to the LEDs10 (duty cycle referring to the percentage of the time that the LEDs areilluminated in proportion to the time they are dark). For example:

-   -   if the available voltage level is too high, the frequency of        pulses to the LEDs 10 can be reduced. Using the inductive driver        circuit described hereinafter, the LEDs 10 will not be        over-driven; or    -   If the available voltage level is too low, the number of LEDs 10        being driven can be reduced, or the duty cycle of the pulses to        the LEDs 10 can be decreased to conserve power.

The power level that LEDs 10 can withstand has to be de-rated with highambient temperatures. Using an ambient temperature sensor, LEDs 10 canbe driven at their optimal levels without fear of damage.

The control circuit 12 also includes the following components:

1. circuitry for receiving data and/or measurements 16 from theenvironmental sensors 14;

2. circuitry for calculating optimal operating parameters 18 for theLEDs 10, based on the environmental data and/or measurements; and

3. circuitry for driving 20 the LEDs 10 in accordance with thecalculated optimal operating parameters.

The actual hardware and/or firmware that is used to implement thecircuitry for receiving data and/or measurements 16 will depend on thegeneral design strategy and upon the nature of the environmental sensors14 themselves. In some cases, the environmental sensors 14 may consistsimply of switches which are actuated when a certain condition arises,which can be handled by the control circuit 12 using a simple digitalinput. In other cases, analogue signals may be provided by theenvironmental sensors 14 which require some conditioning or filtering,an analogue input on the control circuit 12 or external conversion fromanalogue to digital signals. These design issues would be clear to oneskilled in the art from the teachings herein.

Clearly, the control circuit 12 itself could be implemented using adedicated circuit, ASIC (application specific integrated circuit),microcontroller, microprocessor or the like, and any necessarysupporting components. This design choice will generally determine howthe circuitry for calculating optimal operating parameters 18 and thecircuitry for driving 20 the LEDs 10 will be effected. The circuitry forcalculating optimal operating parameters 18, for example, could beeffected in a microprocessor in the manner of actual calculations whichare performed. Alternatively, it could be implemented by indexing astored lookup table.

Microprocessors and microcontrollers are the most logical choicesbecause of their great processing power and programming flexibility.Different models of LEDs will have different performance parameters.Having a programmable controller makes the task of accommodating a newLED model much easier.

The circuitry for driving 20 the LEDs 10 will be determined by thenumber and size of the LEDs 10 (which determines the power required),the manner in which the LEDs 10 are wired, and the patterns that aredesired. LEDs 10 are commonly wired in series, parallel, a combinationof the two, or individually. The invention is not limited by the mannerin which the LEDs 10 are wired. Clearly, wiring the LEDs 10 individuallyprovides the greatest flexibility in the generation of differentpatterns. Ganging LEDs 10 together however, results in much lesscomplexity and less wiring

This circuit provides a solid state warning light with many advantagesover the prior art. Most importantly, it optimizes the light output inview of environmental conditions. This is quite distinct from prior artwarning lights described in the Background, which typically endeavour tominimize the power consumed, and hence, minimize the output light levelwith respect to certain conditions. The prior art does not teach thatthe light level should be optimized, but on the contrary, that it shouldbe minimized—the prior art attempts to set the lighting level at theminimal acceptable level with respect to the ambient light level.

A number of various embodiments of the invention will now be described.These embodiments address a number of the other problems found in theart.

FIG. 2 presents an electrical schematic diagram of a warning light inwhich LEDs are excited by an inductive switch-mode boost circuitcontrolled by a microprocessor. This circuit may be operated from supplyvoltages where the sum of the LED junction voltage drops is greater thanthe supply voltage.

All components and circuitry may be constructed on a singleprinted-wiring circuit board which is referred to herein as anIntegrated LED Module (ILM). The LEDs D1 to DN are driven by an LED BuckBoost Channel (LBBC). Transistor Q1 should be a transistor with thecharacteristic of low on-state resistance (much less than one ohm). L1should be an inductor with low resistance and high inductance value(highest Q factor practical). D1 to DN should be a series branch of LEDsof high output luminous flux and capable of high current operation. Thenumber of LEDs should be chosen so as to have a cumulative forwardjunction voltage drop higher than the supply voltage.

U3 microprocessor (or microcontroller) should be of low powerconsumption and with suitable output pin drive capability to reliablyassert the control pin of transistor Q1 alternately from off-state toon-state. U1 represents an over-current protection device and may be asuitably rated positive-temperature-coefficident fuse. U2 represents alow-power voltage regulator to provide a suitable current supply for themicroprocessor U3.

U4 represents an Analog-to-digital convertor used to detect and measurethe electrical supply voltage. This information is used by themicroprocessor to adjust the pulse duration and pulse repetition rateused to excite the LEDs D1 to DN. The microprocessor U3 may use softwarelook-up tables or an algorithm to determine the optimum pulse timing toapply to the LED excitation circuit. The microprocessor U3 alternatelyswitches the transistor Q1 from off-state to full conduction on-state ata rate of approximately 100 KHz (design frequency can be chosen over abroad range to match the choice of inductors and LEDs).

The high pulse rate (approximately 100 KHz) of the LED excitationcircuit results in a visual effect of apparent constant illumination. Anobserver has no impression of pulsation of the LEDs emitted light.

During the transistor Q1 on-state, current flow increases through theinductor L1 to the common node, developing an electromagnetic field inthe inductor L1. No conduction occurs through the LEDs D1-to-DN at thistime. During the transistor Q1 off-state current flows through theinductor L1 and LEDs D1 to DN causing light to be emitted. A repetitionrate should be chosen so as to allow the electromagnetic field in L1 tocompletely collapse and all current flow through the LEDs to ceasebefore starting a new Q1 on-state.

A discrete rectification diode is not employed in this circuit as thisfunction is performed by the LED junction(s). An output filter capacitoris not employed either as there is no requirement for voltage ripplesmoothing. Hence, the entire excitation circuit is implemented withoutany resistors, capacitors or rectifying diodes.

LEDs are a very efficient and durable light source. Other light sourcesused in the art such as incandescent or halogen bulbs, and xenon flashtubes are less durable and less power efficient.

LEDs however, require a controlled electrical power source foroperation. The inductive excitation circuit of the invention is veryefficient, straightforward in design and inexpensive. This is incontrast to the typical LED driving circuits used in the art whichsuffer from problems such as:

-   -   additional circuit complexity, resulting in unwanted higher        production cost and poorer reliability;    -   a lower electrical-to-luminous power conversion efficiency,        resulting in unwanted higher operating temperatures and unwanted        higher electrical power consumption; and    -   limited ability to operate from a range of electrical supply        voltages.

In particular, the LED driving circuits used in the art are generallyone of the following designs:

-   1. LED constant voltage circuits, which require the use of series    resistors. This design has the poorest efficiency as most of the    electrical energy is wasted as heat;-   2. LED constant current circuits which require the use of additional    circuitry to measure and control electrical power exciting the LED.    Typically, current regulated LED circuits employ series    current-sense resistor and sensitive analog-to-digital conversion    circuits; expensive and complex to build, and having a high parts    count; and-   3. unregulated circuits require heat producing series resistors and    are limited to operation over a narrow range of electrical supply    voltages, therefore limiting their application.

In contrast, the inductive excitation circuit of the invention isinexpensive, has a low parts count, does not use heat producingresistors, and can be monitored and controlled by the microprocessor.The pulsed direct-current nature of the inductive excitation circuitalso enables operation from a wide range of electrical supply voltages;therefore, it can be operated from a wide range of electrical suppliesincluding regular and rechargeable batteries, solar panels andautomotive electrical systems.

Using a microprocessor U3 at the heart of this circuit provides forgreat flexibility. The microprocessor can perform measurements onvarious environmental factors affecting the warning light (such aselectrical supply voltage, ambient temperature, etc.) and automaticallyadjust its operation according to need. These environmental sensors 30are generally mounted on the same circuit board as the microprocessor U3but can also be installed on the housing of the ILM. The microprocessorU3 can also provide additional functionality including the following:

-   1. the microprocessor U3 may excite the LEDs D1 to DN in bursts so    as to produce obvious pulses of light. The bursts may be of very    short duration so as to give the appearance of a “strobe-light”, or    in longer duration bursts to produce a blinking or flashing effect;-   2. the microprocessor U3 could also send and receive information    from a remote control or through a communications channel, making    the warning light part of a network. The ability to communicate over    a network allows the new warning light to respond in useful ways to    instructions from a remote source or to automatically adjust its own    operation to changes in its operating environment in co-operation    with other devices on the network. As part of a network the warning    light can receive commands via a data-communications network (using    interface COM1) to alter its operation, for example, receiving    commands to:    -   a. start or stop operation in response to certain events;    -   b. changing its operation from a strobing effect to a flashing        effect;    -   c. reducing output power in a controlled way during periods of        scarcity of the electrical power supply (low batteries, lack of        light for solar cells or grid brown-out, for example); or    -   d. increasing power output in a controlled way during times of        increased need such as impaired atmospheric visibility.-    The communications port could also be used to transmit data from    the various environmental sensors or advise on the status of the    warning light itself. Communications between the warning light and a    remote control or network may be implemented by a single or    multi-wire interlace or over a wireless link such as infrared (IR)    or radio frequency (RF) link. Many such computer, communication and    instrumentation networks are known in the art;-   3. the microprocessor U3 may include an on-board, time-of-day clock    and calendar allowing the warning light to modify operation in    response to diumal and seasonal requirements; or-   4. additional banks of LEDs 32 could be driven by the microprocessor    U3, with different control signals being sent to different banks of    LEDs. This could be used to generate different patterns or displays    such as direction arrows or chasers. Different colours could also be    used for the different banks of LEDs.

FIG. 3 presents an electrical schematic of a circuit that is similar tothat of FIG. 2, except that it employs an LED Buck Down Channel (LBDC)rather than a LED Buck Boost Channel (LBBC). This circuit is usefulwhere the sum of the LED junction voltage drops may be less than thesupply voltage. This circuit is that same as FIG. 2 except that the LBDCcircuit feeds the LEDs D1 to DN in series with a transistor Q2 and aninductor L2, and employs a voltage level shifting device U5 to bias thetransistor Q2. It also includes a “freewheel” diode DF, which carriesthe reverse recovery current for the LBDC. Otherwise, the circuit is thesame as that of FIG. 2.

FIG. 4 is the same as FIG. 2, except that rather than providing all ofthe components of the circuit on a single board, in the form of an ILM,this Figure presents the division of components where separate LEDModules (LM) 40, and Control Modules (CM) 42 are used. Similarly, FIG. 5presents the division of components that would be used for the circuitof FIG. 3, again, where the LED module (LM) 50 is separate from themodule containing the microprocessor U3 and excitation circuitry,control module (CM) 52.

FIG. 6 presents an exemplary physical layout of a planar warning lightmodule using the LBBC circuit of FIG. 2. In this case only two LBBCcircuits are presented: LBBC1 and LBBCn, but many more could also beused. As shown, the LEDs are preferably arranged adjacent theirrespective inductors L1. Ln and transistors Q1, Qn. The balance of theelectronic components are preferably installed in accessible locationswhich do not interfere with the physical positioning of the LEDs or thepotentially hot excitation components.

FIG. 7 similarly presents an exemplary physical layout of a planarwarning light module using the LBDC circuit of FIG. 3. In this case onlytwo LBDC circuits are presented: LBDC1 and LBDCn, but many more couldalso be used. As shown, the LEDs are preferably arranged adjacent theirrespective inductors L2. Ln and transistors Q2, Qn. The balance of theelectronic components are preferably installed in accessible locationswhich do not interfere with the physical placement of the LEDs or thepotentially hot excitation components.

FIGS. 8 and 9 present top and front views respectively, of a physicallayout of a cylindrical warning light in an embodiment of the invention.A rugged, lightweight housing of extruded aluminum alloy with ananodized surface and a clear, colourless polycarbonate lens would beused to protect the Integrated LED Module (ILM) 60 shown in these twofigures. Silicone gaskets provide weather-resistant joints betweenhousing and lens, and around the cable entry.

The ILM assembly presented in FIGS. 8 and 9 may be constructed withconventional low-cost Printed Wiring Circuit Assembly techniques. Thecylinder is formed by attaching multiple, rigid, LED sub-assemblies 62to a rigid base circuit board 64 by means of multi-pin right-angle pinheaders 66 that provide both mechanical and electrical connectionbetween the circuit boards. This construction technique allows theassembly of an omni-directional warning light module without the needfor costly flexible or bendable circuit board materials.

A warning light of this configuration can be used to emulate a rotatingwarning light without any moving parts. This is done simply byilluminating successive columns of LEDs or groups of columns, in apattern which cycles around the warning light. Being entirely solidstate, this warning light is physically lighter, more durable and lessexpensive than comparable mechanical warning lights.

FIGS. 10 and 11 present top and front views respectively, of a physicallayout of a planar warning light in an embodiment of the invention. Likethe warning light of FIGS. 8 and 9, this warning light would typicallybe encased in a rugged, lightweight housing 70 of extruded aluminumalloy with an anodized surface and a clear, colourless polycarbonatelens 72 would be used to protect the Integrated LED Module (ILM) 74shown in these two figures. Silicone gaskets provide weather-resistentjoints between housing and lens and cable entry. Selectively appliedLight Control Film (LCF) 76 refracts light emitted by the LEDs to modifythe viewing angle. A multi-conductor cable (not shown) may provideelectrical power and connections to a data-communications network.

Most light sources (including LEDs) require a means to control thedirection and intensity of the emitted light. Lenses and reflectors canbe expensive to manufacture and have size and shape characteristics thatlimit their application. Glass lenses, for example, are bulky, heavy,expensive and fragile. Plastic lenses are also bulky and have poorerlight transmission characteristics. As well, injection-moulds forplastic lens have high initial cost. Reflectors tend to be large andbulky and their geometry favours the use of single point-source lighttypes.

Light Control Film (LCF) 76 may be used to reflect and refract lightfrom the LEDs into useful patterns. LCF is a thin transparent film thatcontains microscopic features (micro-louvers, dots or squares, forexample) that control the direction of visible light passing through it.Light entering the film from one side can be emitted from the other sidewith its path altered by a significant angle, for example, beingrefracted by an angle of 30 degrees. The film may be constructed ofpolycarbonate and is available from 3M corp. LCF is thin, rugged andflexible, and can be easily worked to produce a wide variety of lightcontrol effects.

LEDs may also be selected which contain optical lenses integral with thebody of the LED package and so may not require the use of additionallenses or reflectors to focus the emitted light.

An array of planar warning lights may be assembled into a single housingfor use on the roof of a service vehicle to replace the functionality ofa “light bar”. The network capability of the array simplifies theinstallation and maintenance by eliminating the large and heavy bundleof cables traditionally used to control a “light-bar”.

FIGS. 12 and 13 present top and front views respectively of arectangular embodiment consisting of four ILMs 74 in a common housing.Housing 80 may be substantially square, rectangular, cylindrical or anysuitable shape. Light emitted by the LEDs is generally perpendicular toflat planes, but is refracted through 360 degrees by the LCF 76 to forman omnidirectional beacon. A rechargeable electrical storage battery 82located in the center of the assembly can provide electrical power forthe ILMs 74. A Solar Panel 84 mounted onto or forming the top of thehousing may provide electrical power for the ILMs 74 or to recharge thebattery 82. A wireless radio-frequency or infrared link (not shown) mayprovide connection to a data communications network. Such an assemblymay operate for a years of time without any wired connections.

FIGS. 14 and 15 present top and front views respectively of a linearassembly of ILMs 74 in a common housing. ILMs 74 may contain LEDs ofdifferent colours and so be capable of replacing so-called “light-bars”used to signal vehicle identity and operation by means of colour codes(for example, Red and White indicating Polica, Ambulance, Fire equipmentor Blue indicating Snow removal equipment, etc.)

FIGS. 16, 17 and 18 present side, top and isometric views of a warninglight consisting of an array of omnidirectional side-emitting LEDs 90.Each side-emitting LED 90 is mounted on its own circuit board 96 whichis fixed to a heat sink which also serves as a light directing baffle.Successive circuit boards 92 are separated by means of standoffs 94.

This design is easily scalable for any number of LEDs. Different coloursof LEDs could be used to implement a tower of warning signals. Theassembly of FIGS. 17, 18 and 19 could also be enhanced by means ofcylindrical Fresnel lenses or regular lenses.

FIGS. 19 through 23 present various views of an LED module consisting ofan array of LEDs with optical lenses. The array is constructed so as tocontrol the field-of-view.

As shown in the top view of FIG. 20, three or more LED modules 100 canbe mounted on a single heatsink 102, formed to direct the light in thedesired directions. The faceplate 104 serves an aesthetic purpose, aswell as providing physical protection and structure to the assembly. Thefaceplate 104 is mounted on the heatsink by means of standoffs 106.FIGS. 19 and 21 present front and back views respectively of the samedesign. FIGS. 22 and 23 present front and back isometric viewsrespectively, of the same design.

The new warning light may be used in many of the traditional warninglight applications but with the benefit of reduced electrical powerconsumption, lower initial cost, improved reliability and longer life.Additionally, the new warning light may find new applications enabled byits improved functional characteristics.

Reduced power requirements allow longer running time and/or increasedlight output in applications such as battery or solar powered marineinstallations. Reduced initial cost and maintenance requirements improvethe economic feasibility of use of the new warning light in costsensitive and access-restricted environments.

While particular embodiments of the present invention have been shownand described, it is clear that changes and modifications may be made tosuch embodiments without departing from the true scope and spirit of theinvention. For example, one could use polarizing film or shadow maskmounted in front of LEDs for the purpose of contrast enhancement. Thecontrast ratio of the warning signal to the adjacent background has asignificant contribution to the noticeability of a warning light, andthe use of polarizing film, shadow mask or other techniques known in theart would improve the contrast.

1. A warning light comprising: an assembly of light emitting diodes(LEDs); a control circuit operable to drive said LEDs; one or moreenvironmental sensors coupled to said control circuit; said controlcircuit further including: means for receiving data and/or measurementsfrom said environmental sensors: means for calculating optimal operatingparameters for said LEDs, based on said environmental data and/ormeasurements; and means for driving said LEDs in accordance with saidcalculated optimal operating parameters.
 2. The warning light of claim 1wherein said control circuit comprises a microprocessor.
 3. The warninglight of claim 2 wherein said microprocessor includes means forcommunicating over a network.
 4. The warning light of claim 3, whereinsaid microprocessor performs said calculations using a lookup table. 5.The warning light of claim 1 wherein said means for driving includes aninductive excitation circuit allowing the device to operate from a widerange of electrical supply voltages.
 6. The warning light of claim 5wherein said inductive excitation circuit does not require anycapacitors, rectifying diodes or resistors.
 7. The warning light ofclaim 5 wherein said means for driving comprises a buck boost channel,whereby a series-connected assembly of LEDs can be driven by a voltagelower than the cumulative voltage drop across said series connectedassembly of LEDs.
 8. The warning light of claim 5 wherein said means fordriving comprises a buck, down channel, whereby a series of LEDs can bedriven by a voltage higher than the cumulative voltage drop across saidseries of LEDs.
 9. The warning light of claim 1 wherein said one or moreenvironmental sensors includes an analog-to-digital convertor used todetect and measure the electrical supply voltage, and said controlcircuit is operable to adjust power to said assembly of LEDs in responseto the available voltage level.
 10. The warning light of claim 1 whereinsaid means for driving comprises means for providing pulseddirect-current to said assembly of LEDs.
 11. The warning light of claim10 wherein said means for calculating adjusts the pulse timing of saidassembly of LEDs.
 12. The warning light of claim 10 wherein said meansfor calculating adjusts the pulse duration and pulse repetition rateused to excite said assembly of LEDs.
 13. The warning light of claim 1wherein said control circuit is operable to provide separate controlsignals to separate LED modules.
 14. The warning light of claim 1wherein said control circuit is operable to communicate with otherexternal devices and networks.
 15. The warning light of claim 14 whereinsaid control circuit includes means for receiving commands to alter itsoperation.
 16. The warning light of claim 14 wherein said controlcircuit includes means for transmitting data from various environmentalsensors.
 17. The warning light of claim 14 wherein said control circuitincludes means for transmitting data about its own status.
 18. Thewarning light of claim 1, wherein said one or more environmental sensorsis selected from the group consisting of: ambient temperature; internaltemperature; ambient light level; emitted light level; relativehumidity; liquid moisture; mechanical tilt; vibration; physical shock;marine wave height and period; air pressure; solar cell voltage; batteryvoltage; supply voltage.
 19. The warning light of claim 1, furthercomprising a temperature sensor electrically coupled to said controlcircuit, and wherein said control circuit is operable to derate saidLEDs with temperature.
 20. The warning light of claim 1, furthercomprising selectively applied light-control-film to direct and focuslight, rather than expensive and complex curved or circular circuitassemblies, lenses or reflectors.
 21. The warning light of claim 1,wherein said warning light is polygon in cross-section, and includeslight-control-film to refract light from said assembly of LEDsomni-directionally.
 22. The warning light of claim 1 whereinmulti-directional light is provided, said warning light comprising aplurality of LED sub-assemblies on rigid printed circuits, said rigidprinted circuits being connected to one another such that the separateLED sub-assemblies are aimed in different directions.
 23. A warninglight comprising: a plurality of separate LED sub-assemblies on rigidprinted circuits, attached to a base circuit board that provides bothmechanical and electrical connection between the rigid circuit boardsand the base circuit board, said separate LED sub-assemblies beingpointed in different directions; a control circuit operable to drivesaid separate LED sub-assemblies; one or more environmental sensorscoupled to said control circuit; said control circuit further including:means for receiving data and/or measurements from said environmentalsensors; means for calculating optimal operating parameters for saidseparate LED sub-assemblies, based on said environmental data and/ormeasurements; and means for driving said separate LED sub-assemblies inaccordance with said calculated optimal operating parameters; allowingthe assembly of a multi-directional warning light module without theneed for costly flexible or bendable circuit board materials.
 24. Awarning light comprising: an assembly of light emitting diodes (LEDs); acontrol circuit operable to drive said LEDs; one or more environmentalsensors coupled to said control circuit; said control circuit furtherincluding: circuitry for receiving data and/or measurements from saidenvironmental sensors; circuitry for calculating optimal operatingparameters for said LEDs, based on said environmental data and/ormeasurements; and circuitry for driving said LEDs in accordance withsaid calculated optimal operating parameters.